Wireless optical communication is a short-distance high-speed wireless optical communications technology that is developed based on a light emitting diode (LED) technology. A basic principle of wireless optical communication is to use flash of an LED light source to communicate by virtue of a characteristic that an LED lamp switches faster than a fluorescent lamp and an incandescent lamp. In short, light represents binary 1, and absence of light represents binary 0. After a high-speed optical signal that includes digital information undergoes optical-to-electric conversion, information can be obtained. In the wireless optical communications technology, data is hardly interfered with or captured, and an optical communications device is easily producible but is not easy to damage or degauss, and therefore, may be used to make a wireless optical encryption key. Compared with microwave technologies, the wireless optical communication has relatively rich spectrum resources, which is incomparable with general microwave communication and wireless communication. In addition, the wireless optical communication is compatible with any communications protocol and applicable to any environment. In terms of security, compared with conventional magnetic materials, the wireless optical communication is free from a degaussing problem, without any need to worry about theft of communication content. A wireless optical communications device is flexible, portable, cost-efficient, and suitable for massive popularized application.
With rapid popularization of wireless optical communication, a technology of sending a wireless optical signal by using an LED lamp of a portable electronic device such as a mobile phone has been proposed. When the LED lamp in the portable electronic device is turned on or off, an on duration or an off duration changes randomly, but the durations may be controlled within a specific range. Therefore, a wireless optical signal that represents data information may be sent by the LED lamp of the terminal by using a specially set encoding mode.
Wireless optical communication has a broad application prospect in various fields. Currently, a relatively mature application is an access control system. The Chinese patent application CN102682505 discloses a method for applying an LED wireless optical communications technology to access control identity authentication, and the Chinese patent application CN102693567 discloses a communication encoding and decoding method for this access control system.
However, on one hand, because a brightness duration and a dimness duration of an optical signal sent by the LED lamp of the portable electronic device change randomly, a recognition ratio of the optical signal is relatively low. On the other hand, strobe features of LED lamps in different electronic devices are different, and a value range of a receiving parameter that is set on at a receive end of light is largely widened to adapt to a transmit end, which reduces performance of some portable electronic devices with excellent strobe features in order to adapt to the receiving parameter. Even so, there are still portable electronic devices that mismatch the parameter, and their signal recognition ratio is still relatively low. Moreover, when the parameter of the optical signal sent by the LED lamp changes, the receive end needs upgrading, which makes system upgrade and maintenance become very complicated.